Method for the production of normally liquid hydrocarbons from gaseous or lower boiling hydrocarbon materials



Patented May 28, 1935 UNITED STATES METHOD FOR THE PRODUCTION OF NORMALLY LIQUID HYDROCARBONS FROM GASEOUS OR LOWER BOILING HYDRO- CARBONMATERIALS Per K. Frolich, Elizabeth, N. J., assignor to Standard OllDevelopment Company No Drawing.

Application September 10, 1930,

Serial No. 481,070

.10 Claims.

The present invention relates to an improved method for the productionof normally liquid hydrocarbons from gaseous or lower boilinghydrocarbon materials and more specifically to a process for theproduction of liquid hydrocarbons boiling within the range suitable forcommercial gasoline from gaseous or low boiling hydrocarbons. My processwill be fully understood from the following description.

In a prior application Ser. No. 438,650 filed March 24, 1930 now PatentNo. 1,869,681 the present inventor disclosed an advantageous process forthe manufacture of low boiling materials liquid at normal temperaturesand pressures from normally gaseous hydrocarbons such as ethane,propane, butane and the like which occur in large volume in natural orrefinery gases. These materials are used at the present time as fuel dueto the fact that the hydrocarbons are normally gaseous or boiling at toolow a temperature to be included in commercial gasolines. The presentapplication is an improvement over the process disclosed in my priorapplication above noted for accomplishing the same purpose with greaterease and economic advantage.

My process consists in a series of steps as follows: First theconversion of saturated materials such as ethane, propane and butaneinto olefins, which is accompanied by the liberation of free hydrogen.The second step comprises removal from this gaseous mixture of the freehydrogen and the third step comprises polymerization of hydrogen-freegas to form normally liquid hydrocarbons suitable for commercial motorfuel. Each of the said steps will be separately described. The first, orcracking step may be carried out in any desired manner, for example;merely by heating to a decomposition temperature say from approximately500 to 1000 C. either with or without pressure and in the presence orabsence of catalysts, preferably used in non-ferrous tubes or ferrousmetal tubes containing 8% of chromium or more. The preferred method,however, is that disclosed in the copending application Ser. No. 360,000of the present inventor with B. O. Boeckeler which was filed May 2,1929. This process comprises dehydrogenation of hydrocarbons by the useof certain catalytic agents at temperatures within the approximate rangeof 450 C. to 700 C. with or without pressure (up to 250 lbs. per squareinch). Metallic catalysts have been found satisfactory and the mixtureof metallic oxides after reduction with methanol, hydrogen orhydrocarbon vapors or otherwise, are preferred although other types ofdehydrogenation catalysts may be used. Catalysts containing zinc andanother metal which has two or more valences are particularly desirable,such as 30 mol. percent zinc, '70 mol. percent of chromium or otherproportions of the same elements, or zinc and molybdenum or tungsten,vanadium and the like. The rate of flow of the gases in this process ispreferably very rapid, for example; above about two volumes ofhydrocarbon vapor per minute per volume of reaction space and under suchconditions it is observed that two or more atoms of hydrogen are removedfrom the hydrocarbon molecule with substantially no decomposition of thecarbon structure, that is to say, substantially no hydrocarbons of fewercarbon atoms are produced.

This process may be used on pure hydrocarbons or mixtures of two or morehydrocarbons and diluent gases including hydrogen, nitrogen, methane orother gases may be used. In this way the highest yield of olefins andconsequently the lowest yield of methane which forms as a waste productin the process is obtained.

The gas obtained from the first step of my process comprises a mixtureof olefins, unreacted paraflinic hydrocarbons and hydrogen. Removal ofthe major quantity of the free hydrogen comprises the, second step andthis is accomplished in a particularly desirable manner by the additionof carbon monoxide, carbon dioxide or a suitable mixture of the twomaterials either alone or with other substances acting as diluents suchas nitrogen, steam and the like. The gas mixture is passed over asuitable catalyst such as will be disclosed below by which free hydrogenis converted into methane by reaction with the oxides of carbon.

In the operation of the hydrogen removal step I have found that thereaction operates successfully either at atmospheric or at higherpressures, but preferably it is carried out under pressures of severalatmospheres and may be carried out at considerable pressures of 100atmospheres or more. The catalysts most suitable for my process aremethanizing catalysts and consist of metallic nickel or of nickel oxidein finely divided form, but it is desirable to add additional agentssuch as aluminum oxide, thoria or other rare earths, chromium, vanadium,tungsten, molybdenum, manganese, boron and similar oxides preferably inamounts less than the nickel or its oxides. The temperature ispreferably below 400 C. and operates satisfactorily within a range fromabout 200 to 350 C. When carried out on a small scale there is nodifficulty in keeping the apparatus cool as the radiation loss isgenerally sufiicient for the purpose, but when large tubes are used andrelatively large volumes of gas are treated it is desirable to providesome method of cooling so as to prevent an excessive rise intemperature. It is desirable also to desulphurize the gas and this stepmay be accomplished either after the cracking operation or before suchan operation,-as will be understood. Any desirable means ofdesulphurization may be used, for example a gas may be washed with sodasolution or mixture of sodium carbonate containing iron oxide. 3 v

The third or polymerization step may be carried out under atmosphericpressure or at higher pressure, for example above 100 pounds per squareinch, but preferably in the range from 300'to 1000 pounds per squareinch. The temperature may vary considerably within the approximatelimits of 500 to 900 C. and it has been found that. with higher pressureit is generally desirable to use somewhat lower temperatures. The timeof reaction may vary widely, for example, from less than 1 minute athigher temperatures to 25 or minutes orlonger at lower temperatures andcontact materials may be used, preferably of a metallic character havinga high heat conductivity in order to maintain uniform temperaturesthroughout the reaction chamber.

Using the present process, comprising the three steps described above,yields of l to 8 gallons or more of liquid products may be obtained perthousand cubic feet of propane orv gases comprising, ethane, propane andbutane. One

- half or more of the'distillate is generally sumcientlv low boiling forcommercial gasoline and is ordinarily admirably suited for use ininternal combustionengines by reason of its anti-detonation qualities.It may be used alone or may be blended with other materials available inpetroleum refineries. The higher boiling material is sometimes of atarry nature. 1

As an example of the operation of my process propane is passed through atube of copper or other metal such as chrome steel or ceramic materialheated to a temperature of about 800 C. The outgoing gas has thefollowing composition:

Percent (111'- 13 0on1 Ha 30 CH4+CaHc 31 This gaseous mixture is thenmixed with about 15% of its volume of carbon monoxide producing a ratioof about 2 mols of free hydrogen per moi. of carbon monoxide and aftermixing this gas is passed through a soda solution to remove sulphurcompounds.- The mixture is now compressed to a pressure of about 600pounds per square inch and passed through a chamber preferably in theform of tubes fllled with a catalyst comprising a mixture of about 70%of nickel bxide and 30% of aluminum oxide. The temrature is maintainedat about 300 C. and the rate of flow is adjusted to give a substantialremoval of hydrogen. The eiliuent gas has the following analysis on adry basis.

Percent (11H: 15.4 Cal-T4 30. 6 CH4+C2H 52-54 H 1 Below about 2 Thismixture is now passed at a rate adjusted liquid product shows that aboutthereoi boils within the range of 85 to 220 C. the mixture is highlyunsaturated and with the bromine number over 100. It is light in color.After finishing at ordinary methods known in the petroleum industry andcut to a final boiling point of about 200 C. it is admirably adapted asan anti-detonating fuel for internal combustion engines, it beingequivalent in antidetonating value to a naphtha from an ordinarysweet'crude such as mid-continent crude to which at least 80% of benzolhas been added.

As has been indicated above carbon dioxide may be used in the process inplace of carbon monoxide as described in the previous examples.

With pressure a smaller excess may be used.

It is preferable to use CO for this purpose because it is readilycombustible and the resulting mixture of methane and excess CO may beused,

as a source of fuel for preheating the raw gases and keeping thereactors up to temperature.

The entire series of steps may be carried out at atmospheric or higherpressures, say

pounds per square inch or if desired, one or more steps may be at lowpressure, while the other or others are accomplished at higher pressure.It is particularly desirable to conduct the cracking steps atatmospheric pressure or below 100 pounds, scrub with alkali to removesulphur, remove free hydrogen at the same pressure and subsequentlypolymerize at pressures above 100 pounds. Y

My invention is not to be limited by any theory of the mechanism of thereactions nor to any specific example which may have been given forpurpose of illustration, but only by the 101- lowing claims in which Iwish to claim all novelty inherent in my invention.

1 claim:

1. An improved process for obtaining valuable higher boilinghydrocarbons from gases containing large amounts of lower boilingsaturated hydrocarbons containing more thanone carbon atom whichcomprises cracking the lower boiling materials whereby a substantialproportion of unsaturates is formed together with free hydrogen,subsequently adding to the mixture a gas rich in an oxide of carbon,causing the oxide of carbon and hydrogen to react and then poiymerizingthe unsaturated hydrocarbons.

2. An improved method for converting low molecular weight parafilnhydrocarbons containing more than one carbon atom to higher molecularweight hydrocarbons which comprises the steps of converting theparafilns to oleflns and hydrogen by the action of heat, removing freehydrogen by reaction thereof with carbon monoxide and then polymerizingthe hydrogen free mixture.

3. An improved process for converting low molecular weight saturatedhydrocarbons containing more than one carbon atom into higher molecularweight hydrocarbons comprising first converting saturated hydrocarbonsinto oleflns by action of heat at temperatures above about 450 8. Animproved process for obtaining valuable higher boiling hydrocarbons fromlower boiling 0. and below about C. then mixing a gas rich in carbonmonoxide therewith to provide an excess of CO over the ratio of 1 CO to2 H: and passing the mixture over a methanizing catalyst at temperatureswithin the limits of about 200 to 400 0. whereby the hydrogen content ofthe gas mixture is reduced to below about 2% and poly-1 merizing theremaining olefins at temperatures within the appropriate limits of500-900' C,

4. Process according to claim 1 in which the hydrogen in the gases issubstantially completely removed.

5. Process according to claim 1 in which a methanization catalystcomprising a major proportion of nickel is used to cause reaction 01'the oxide of carbon with hydrogen.

6. Process according to claim I in which conversion of saturated toolefin hydrocarbons is carried out at pressures below 250 lbs. persquare inch the dehydrogenation at pressures between the approximatelimits of several atmospheres and 100 atmospheres, and thepolymerization at pressures between the approximate limits of 300 to1000 lbs. per sq. in.

'7. Process according to claim 1 in which the gases resulting from thefirst step of the process are desulphurized before the hydrogen removalstep.

and gaseous saturated hydrocarbons containing more than 1 carbon atomcomprising converting the saturated into olefin hydrocarbons by theaction of heat at temperatures above about 500 C. and below about 1000'C. at pressures below about 250 pounds per square inch, passing the gasmixture througha suitable desulphurizing agent, compressing the purifiedgas to pressure between about 300 and 1000 pounds per square inch,mixing carbon monoxide therewith in proportion required to provide asubstantial removal of hydrogen, passing the mixture over amethanization catalyst at temperature of 200.- to 350 C. and thenpolymerizing the remaining olefins at temperatures above 500 C. andbelow 900 C. n

9. Process according to claim 1, in which th cracking step is carriedout at temperature between the approximate limits at 500 to 1000 C. inthe presence of a catalyst consisting of zinc and a metal element of thesixth group having two or more valences. I

10. Process according to claim 1, in which petroleum refinery gases areused as a raw material.

PER K. FROLICH.

